nervous

the system consists of 2 principal divisions called

Because the brain and spinal cord occupy a midline or central location in the body, they are together called the

Similarly, the usual designation for the nerves of the body is the

consists of structures that regulate the body’s autonomic or involuntary functions.

consists of the brain and spinal cord, which occupy the dorsal body cavity and act as the integrating and command centers of the NS. They interpret incoming sensory information and issue instructions based on past experience and current conditions.

, the part of the NS outside the CNS, consists mainly of the nerves that extend from the brain and spinal cord. S

carry impulses to & from the spinal cord.

carry impulses to & from the brain. These nerves serve as communication lines

consists of nerve fibers that convey impulses to the CNS from sensory receptors located in various parts of the body.

Sensory fibers delivering impulses from the skin, skeletal muscles, and joints are called

transmitting impulses from the visceral organs are called

Carries impulses from the CNS to effector organs, muscles and glands.

allow us to consciously, or voluntarily, control our skeletal muscles (aka voluntary nervous system).

regulates events that are automatic, or involuntary, such as the activity of smooth & cardiac muscle and glands (aka involuntary NS).

in the CNS are “lumped together” as neuroglia, literally, “nerve glue.”

includes many types of cells that generally support, insulate, and protect the delicate neurons (aka Glia).

are star-shaped cells that account nearly half of the neural tissue.

Spiderlike phagocytes that dispose of debris, including dead brain cells and bacteria.

These glial cells line the cavities of the brain and the spinal cord

Glia that wrap their flat extensions tightly around the nerve fibers, producing fatty insulating covering called myelin sheaths

form the myelin sheaths around nerve fibers that are found in the PNS.

act as protective, cushioning cells.

also called nerve cells, are highly specialized to transmit messages (nerve impulse) from one part of the body to another.

is the metabolic center of the neuron. It contains the usual organelles except for centrioles

is the neuron process that convey incoming messages (electrical signals) toward the cell body

generate nerve impulses and typically conduct them away from the cell body

four major regions

are the most superior part of the brain and together are a good deal larger than the other three brain regions combined.

aka interbrain, sits atop the brain stem and is enclosed by the cerebral hemisphere.

encloses the shallow third ventricle of the brain, is a relay station for sensory impulses passing upward to the sensory cortex. We can recognize whether the sensation is pleasant or unpleasant.

s (literally, “under the thalamus”) makes up the floor of the diencephalon.

It is also center of many drives and emotions, and as such it is an important part of the so called

Its structures are the midbrain, pons, and medulla oblongata.

a small part of the brain stem which extends from mammillary bodies to the pons inferiorly.

It is a rounded structure that protrudes just below the midbrain. means “bridge,” and this area of the brain stem is mostly fiber tracts

the most inferior part of the brain stem.

It provides the precise timing for skeletal muscle activity and controls our balance and equilibrium. Because of its activity, body movements are smooth and coordinated.

The three connective tissue membranes covering and protecting the CNS structures.

The nerves connecting the brain and spinal cord to other parts of the body constitute the peripheral nervous system.

ANS consists of certain motor neurons that conduct impulses from the spinal cord or brainstem to the following kinds of tissues: